Atherosclerosis is a progressive disease process in which the flow within the lumen of an artery becomes restricted by a blockage, typically referred to as an atherosclerotic plaque. In the heart, as well as the periphery, a blockage of an artery can result in pain, disfunction and even death. Numerous methods have been employed over the years to revascularize the tissue downstream of an arterial blockage. These methods include bypass grafting using artificial, in-situ venous, or transplanted venous grafts, as well as angioplasty, atherectomy and most recently, laser transmyocardial revascularization. Bypass grafting has been extremely successful; however, the procedure requires extensive surgery. Recently, newer techniques such as the transthoracic endoscopic procedure being pursued by the companies, Heartport, Inc. and Cardiothoracic Systems, Inc., illustrate the need for a less invasive method of bypassing coronary vessels. These procedures are very difficult to perform, and may not be widely applicable. While transmyocardial laser revascularization, a technique in which small holes are drilled through the wall of the heart, looks promising, the method of action is not yet well understood, and problems exist with the use of laser energy to create the channels. Yet clinicians are still very interested in the technique because it has the potential to be minimally invasive, and does not require the patient to be placed on cardiopulmonary bypass.
In the 1970s several cardiovascular surgeons experimented with the use of cardiac veins for revascularization. The procedure was for use on patients which had severally diffuse stenotic coronary vessels. The technique involved using an intervening graft from the internal mammary artery or an aortic attachment to a saphenous vein. Instead of sewing the grafts to the distal coronary artery, the grafts were attached to the coronary or cardiac vein in the same location. The proximal portion of the vein was then ligated to prevent a shunt, and the patient was then taken off cardiopulmonary bypass, and the chest was closed. In this model, the veins were xe2x80x9carterializedxe2x80x9d, allowing flow in a retrograde fashion in an effort to bring oxygenated blood to the venules and capillaries of the heart. The success of this technique varied greatly, and was for the most part abandoned. Problems included stenosis at the anastomosis, intracardiac hemorrhages from ruptured venules, and thrombosis of the grafts.
The devices, systems and methods proposed in this disclosure suggest a new method of percutaneous revascularization. Here, the cardiac veins may either be arterialized, or may be simply used as bypass grafts. There is no literature to suggest that this has ever been attempted. While in-situ bypass grafts have been made in periphery, still an incision is made to attach and ligate the vein ends. Another procedure which bears some resemblance to this technique is called the TIPS procedure transjugular intrahepatic portosystemic shunt. In this procedure a stent is advanced into liver tissue to connect the portal vein to the inferior vena cava. While this procedure can be accomplished percutaneously, it is not for the purpose of revascularization of an organ or to bypass a blockage within a vessel, does not permit retrograde flow within either of the two vessels, is not performed with an accompanying embolization, and requires the use of a stent. Further, the devices and methods used in that setting are too large and do not have the directional capability necessary for use in smaller vessels such as those found in the heart.
Open surgery was for many years the only way to gain access to tissues to perform a surgical maneuver. With the advent of optics, various endoscopic procedures were developed. Initially, these procedures utilized natural orifices such as the urinary tract, oral cavity, nasal canal and anus. Most recently, new techniques using transabdominal and transthoracic ports have been developed. These thorascopic or laporoscopic procedures essentially use instruments which are long shafted versions of their counterparts in open surgery. General anesthesia is usually required, and there are still several smaller wounds which require healing.
Another problem that exists with this approach is the identification of anatomically consistent reference points. For precise surgery, such as in the brain, a frame is usually attached to the patients head to provide this reference. More recently, a xe2x80x9cframelessxe2x80x9d system has been developed which utilizes a much smaller frame mounted with several light emitting diodes (LEDs). The LEDs are correlated to LEDs on the instrument itself using three cameras mounted to the ceiling. This aids in the correlation of the frame to the landmarks, and assures proper positioning of the instrument. While this seems like an extensive effort, it underlines the importance of gaining access to the exact location desired.
Traditionally, the vascular system has been entered for the sole purpose of addressing a vascular problem. Angioplasty, atherectomy, stents, laser angioplasty, thrombolysis and even intracardiac biopsy devices have all been designated for intravascular use.
To date, there are several available schemes for closing off openings, vessels or tubular structures within the body involved in, for instance, the revascularization process. One method utilizes externally applied apparatuses such as staples, clips, sutures or devices which compress the opening externally and apply energy to weld them shut, for example, the Keppinger Forceps. While these methods are very successful, they all require access to the structure from the outside. However, this may not always be possible during certain catheter based inventions.
Another method, compatible with the catheter approach, involves the application of intraluminal devices such as detachable coils, balloons, injectable glues or emboli. These solutions are all limited by the requirement that a foreign object must be used to create a blockage. Moreover, the presences of a foreign object within the body, may at a later time, cause other problems. For example, these devices may become dislodged, or may cause a sever tissue reaction which can be of significant concern.
A device, system and method are provided for utilizing the vascular system as a conduit through which an intervention can be rendered within and beyond the vascular wall. In accordance with one embodiment, a device is introduced into the vascular system at a convenient entry point and is advanced to a particular target location at which point an opening is created to allow the passage of the device or another device or devices through or around the port into the space beyond the interior of the vessel. In one embodiment, a system is used to act as an access port to the space through which a procedure may be performed. Such a procedure may be worthwhile for cooling or ablating a volume of tissue, injecting or infusing a drug, substance or material, cutting, manipulating or retrieving tissue, providing access for endoscopic visualization or diagnosis, the placement of an implantable or temporary device, creating an alternative tract through which blood may be conducted for the purpose of revascularization or for performing some other surgical procedure. In another embodiment, the system is used to achieve an extraliminal percutaneous bypass. More particularly, the system is used to simultaneously achieve a second opening in an adjacent vessel proximate to the first opening so that an anastomosis channel may be created between the two vessels or conduits for the passage of blood therethrough. Such a procedure may be useful for creating alternative vascular channels to provide alternative revascularization routes, such as in the heart between the coronary arteries and cardiac veins, or in the periphery between adjacent veins, conduits and/or arteries. In one embodiment of the invention, the vessel with the second opening may be an in-situ vessel, a natural or artificial graft segment, or a transplanted vessel, all of which having been joined to the vessel with the first opening in a side-to-side manner. In other words, the two adjacent vessels, each having a substantially same size opening created by the system, may be maintained in approximation in a relatively parallel manner rather than the conventional end-to-side manner. With further specificity, such a system may be used to bypass coronary arteries and provide for cardiac venous arterialization, or segmental grafting. In addition, the stability of vascular supply orientation to anatomic landmarks provides a simple method of repeatedly accessing perivascular structures under imaging or other guidance. This may be particularly useful for accessing areas within the brain, kidney, lung, liver, spleen as well as in other tissues, and represents a significant advantage over tissue marking localization, external frames or so-called xe2x80x9cframelessxe2x80x9d external instrument orientation systems. In a further embodiment, the system is used to create an opening in the vessel proximally, tunneling through the tissue adjacent to the vessel, and re-entering the vessel at a distal point. This may be useful for providing an alternate path for blood flow around a lesion with a vessel. A final embodiment of the invention includes a system for closing off an opening such as a lumen of a vessel subsequent to the creation of an alternate revascularization route through which blood may flow around a diseased lesion. The system may use a suction mechanism to first pull the walls of the vessel so that the lumen may be temporarily closed. The system then provides means to securely fix the walls against one another to close off the lumen.
In accordance with one particular embodiment of the invention, there are provided methods and devices for transmyocardial revascularization, whereby transmyocardial passageways or bore holes are formed between one or more coronary blood vessels and one or more chambers of the heart, such that blood from the chamber(s) of the heart will flow through the transmyocardial passageways, thereby enhancing the perfusion of that region of the myocardium. In some instances, this may be accomplished by passing a passageway-forming catheter of the present invention through the coronary sinus and into a coronary vein. Thereafter, the passageway-forming catheter is utilized to form a plurality of transmyocardial passageways or bore holes from the coronary vein into a chamber of the left heart, preferably the left ventricle. Thereafter, the passageway-forming catheter is removed and the coronary vein is permitted to remain without occlusion, embolization or ligation, such that oxygenated blood from the left the left ventricle will flow freely through the transmyocardial passageways, through the coronary vein, and back into the coronary sinus. In this manner, a continual and unobstructed flow of arterial blood will be permitted to pass from the left ventricle, through the transmyocardial passageways, thereby providing for enhanced oxygenation and profusion of that region of the myocardium.